Heterosporium asperatum. By Mr. G. Massee. 581 
rule a germ-tube issues from each end of tlie spore, a third being 
sometimes formed from an interstitial cell. When germination takes 
place in water, whether in an artificial culture or in a drop of water 
on the surface of a leaf of the host-plant, the germ-tubes are very- 
slender, rarely more than 1*5 p thick, equal, simple or sparingly 
branched, spirally curved, transverse septa very rare, and the fusion 
between originally distinct tubes or branches very rare, or in most 
cases entirely absent (figs. 4 and 5). About two days after germina- 
tion has commenced, one or more short lateral branches spring at 
right angles from the germ-tubes ; these may be considered as 
specialized sporophores. The apex of each sporophore becomes 
slightly incrassated, and within a day produces several simple or 
branched concatenate chains of elliptical, pale olive, smooth secondary 
spores, measuring about 3 by 1 • 5 p when mature. These secondary 
spores are developed in acropetal order (fig. 4 a). 
The mode of germination, relative thickness of the germ-tubes, 
and number of chains of secondary spores vary considerably, depending 
on the medium in which germination takes place, the characters being 
constant within certain limits in each case. 
When the spores germinate in a sterilized solution of the host- 
plant ( Smilacina stellata), the germ-tuhes measure 5-6 p in diameter 
at the point of origin from the spore, become elongate, never spirally 
twisted, and gradually taper to the apex ; transverse septa are 
abundant ; the clusters of secondary spores are about equal in number, 
and the secondary spores of the same size as those produced on the 
very slender germ-tubes formed by spores germinating in pure water 
(fig. 3). In both instances sporophores bearing clusters of secondary 
spores are not unfrequently produced directly by interstitial cells of 
the spore without the intervention of a germ-tube (fig. 3 a + and 
fig. 5a+). 
Spores germinating in a solution of sunflower leaf produce a 
single germ-tube from the basal cell of the spore, the tube is 4-5 p 
thick at the point of origin from the spore, sparingly branched, 
tapering, straight, transversely septate, and usually bearing three or 
four sessile whorls of branched chains of secondary spores. These 
secondary spores when placed on moistened portions of the leaf of a 
sunflower germinated as usual, but there was no evidence of the germ- 
tubes having penetrated into the interior of the leaf, but similarly 
produced resting spores readily infected the leaves of the species of 
host -plant from which the material that produced the resting spores 
was obtained. This experiment, with others of a similar nature, 
proves that the secondary spores may, without any disadvantage, be 
produced in media differing widely from that in which the mother- 
spores were produced ; and, furthermore, in some instances it was 
observed that secondary spores so produced germinated more readily 
on the normal host-plant, and produced more vigorous mycelium, 
